Prior to setting forth a short discussion of the related art, it may be helpful to set forth definitions of certain terms that will be used hereinafter.
The term “capturing device” as used herein, is defined as any hardware combination of optics and sensor that is configured to produce electrical signals representative of a scene in a pixel array format. Specifically, a capturing device as discussed herein, does not include any image processing capability implemented therein beyond converting the raw data a data format appropriate for conveying.
The term “microbolometer detector” as used herein, relates to a detector which includes an array of pixels, sealed in a vacuum package.
Infrared radiation with wavelengths typically between 7.5-14 μm strikes the detector material, heating it, and thus changing its electrical resistance. This resistance change is measured and processed into temperatures which can be used to create an image. Unlike other types of infrared detecting equipment, microbolometers do not require cooling
Many thermal imaging cameras make use of microbolometer detectors. Microbolometer detectors suffer from inherent technological issues which make them difficult to work with. When trying to transform the microbolometer readings into good image quality, the raw data captured from the detector has to be corrected with corrections algorithms and correction data sets. Typical corrections are non-uniformity correction (NUC), bad pixel replacement (BPR) and the like. These corrections are specific to each individual detector, and need to be prepared in a special calibration environment, as it requires special tooling and knowhow (Oven, Blackbody, software and the like). More often, corrections are required not only per specific detector, but may also be needed for a specific combination of detector and lens.
Currently available thermal imaging cameras are comprised of a lens, a detector and electronics. The electronic circuitry which is required for capturing and processing the raw IR data and turning it into a video signal is often called IR Engine or IR core. IR engines include a microbolometer detector which is mounted onto a PCB board integrated with additional appropriate circuitry needed for operating, controlling, powering, and reading the detector. Since currently available detectors provide raw data using a parallel electrical interface, either digital or analog the IR engine includes some computing platform, such as FPGA, ASIC, DSP, CPU, and some form of memory in order to be able to perform the above mentioned corrections, as well as other signal and image processing tasks. The fast development of global consumer electronics market brought the availability of strong processing power to the hands of millions of users. Such processors can well replace the processing functions of an IR Engine.
Another challenge for making thermal imaging available for consumers is the power requirements of a microbolometer based thermal imaging device. Due to its way of operation typical IR engine consume 0.6 W or above. Today's consumer electronics are often powered by low power batteries, as for example mobile cellphones, smartphones, tablets, etc. Adding thermal imaging capabilities to a mobile device as an add-on is therefore a challenging task.